As is well known, motorized garage door operators automatically open and close a garage door through a path that is defined by an upper limit and a lower limit wherein the limits can be identified electrically or mechanically. The lower limit is established by the floor upon which the garage door closes. The upper limit can be defined by the highest point the door will travel which can be limited by the operator, a counterbalance system, or the door track system's physical limits. The upper and lower limits are employed to prevent door damage resulting from the operator's attempt to move a door past its physical limits. Under normal operating conditions, the operator's limits may be set to match the door's upper and lower physical limits. However, operator limits are normally set to a point less than the door's physical upper and lower limits.
Systems used to set operator limits are composed of switches used to terminate travel in the up and down directions. These mechanical switches are adjustable and can be used by the consumer or an installer to “fit” the door travel to a garage opening. But these switches have a limited life span. Metal fatigue and corrosion are the most likely causes of switch failure. Another drawback of mechanical switches is that they can be wired in series with the motor which creates high current draw across the contacts of the switch causing the contacts to fail. A further limitation of limit switches is that the up and down limits, which must be set manually, can be improperly set or misadjusted.
Other limit systems employ pulse counters that set the upper and lower travel of the door by counting the revolutions of an operator's rotating component. These pulse counters are normally coupled to the shaft of the motor and provide a count to a microprocessor. The upper and lower limits are programmed into the microprocessor by the consumer or installer. As the door cycles, the pulse counter updates the count to the microprocessor. Once the proper count is reached, which corresponds to the count of the upper and lower limits programmed by the consumer or installer, the door stops. Unfortunately, pulse counters cannot accurately keep count. External factors such as power transients, electrical motor noise, and radio interference often disrupt the count allowing the door to over-travel or under-travel. The microprocessor may also lose count if power to the operator is lost or if the consumer manually moves the door while the power is off and the door is placed in a new position which does not match the original count.
As described above, there are a number of methods of determining the travel limits of a garage door. The main concern, consistently addressed, is to determine whether the door is open or is completely closed. One method addresses this with limit switches placed at the upper and lower travel limits of the door. These limit switches can be installed in the doors path or operated off of a reduced travel jackshaft internal to the operator housing. These limit switches can only indicate whether the door is open or not open, or closed or not closed. Such a system cannot indicate where the door is, if the door is neither fully open nor fully closed. There are also magnetic sensors that can send a signal when in close proximity to each other or when the door attracts the magnet due to the door's proximity to the magnet. These devices also are limited to the indication of either the door being closed or not closed. These types of travel limit devices are sometimes connected to indicator lights to give a remote signal as to whether the door is opened or closed and whether the door is not opened or not closed, but no indication is provided as to the door's exact position between the travel limits.
It is foreseeable to use an encoder or pulse counter that is already incorporated into many of these devices to count the rotation of the motor or other rotating components to determine the travel distance of the door and therefore the door's position. But, as noted, these pulse-counting devices can lose count or need to be reset any time power is lost. For example, if a door is closed and power is lost, when the power comes on the operator does not know if the door is open or closed until the motor is started and the door either stalls or begins to move.
The systems and methods generally discussed above are disclosed in the following patents.
U.S. Pat. No. 6,166,634 discloses an improved garage door signaling device comprising a switch actuable upon opening of the garage door, a transmitter actuable by said switch to transmit a signal indicating that the door is open, a receiver located at a desired location remote from the garage door providing an audiovisual warning when the garage door is not in the closed position, and means for energizing the garage door signaling device. However, the audiovisual device provides no specific indication of door position as the door moves.
U.S. Pat. No. 6,161,438 discloses an internal entrapment system for a door movable by a repeatable force that includes a force generating device for transferring the door between a first and a second position. A trolley arm connected between the force generating device and the door is continually strained during movement of the door. A sensor mounted on the trolley arm generates a signal representative of the strain applied to the trolley arm. A processor receives the strain signal for comparison to a predetermined threshold, when the strain signal exceeds the predetermined threshold, the processor at least stops the force-generating device. A potentiometer is coupled to the door for determining a plurality of positional locations of the door between the first and the second positions, wherein the processor correlates the position of the door with the strain signal for use in comparison to the predetermined threshold. A power supply provides electrical power to the force generating device, the sensor, the processor, and the potentiometer, and a decoder/amplifier circuit, which also receives electrical power from the power supply and receives the strain signal for conversion into a format acceptable for use by the processor. However, no external output for indicating door position, via the potentiometer, is made.
U.S. Pat. No. 6,064,316 teaches an access control system that has at least one door associated with a secured area, each door having a strike plate, a host computer, at least one door control module coupled to the host computer, one door control module for every door, and at least one door reader coupled to the door control module to activate the strike plate to release the door. The access control system further has at least one electro-mechanical key to independently actuate a lock that corresponds to the door(s) and a master-keying device to rekey the lock that corresponds to door(s). The host system records information selected from the group consisting of time of entry, place of entry, identification of entered party, and/or any combination thereof. In addition, a door knob and mechanical locking mechanism selectively latches and unlatches the locking mechanism and can be actuated with a mechanical key. The system also includes circuitry to actuate the locking mechanism to selectively latch so that the door can open, wherein the circuitry is actuated by an electrical signal transmitted by an electrical key, and wherein the electrical signal is communicated by an electrical contact extending through the mechanical locking mechanism. The circuitry is powered by a battery, which can be removed without disturbing or actuating the unlocking mechanism. The contact is an insulated electrical wire that extends through the locking mechanism to the circuitry. All of the circuitry discussed can be integrated onto a single, monolithic piece of silicon in a multi-chip or single-chip format. A master-rekeying device has input/output circuitry to receive and transmit electrical signals, and circuitry coupled to the input/output circuitry to record a list of security passwords in order to check passwords against the list and a memory to store data; and the input/output circuitry also receives and transmits electrical signals to a host computer. However, no discussion is provided of a device that blocks an actuation signal to prevent door movement.
U.S. Pat. No. 5,929,580 discloses an internal entrapment system for a garage door operator and includes a motor for transferring a garage door between first and second positions. Also included is a pulse counter for detecting a speed of the garage door during transfer between first and second positions; a potentiometer for determining a plurality of positional locations of the garage door during transfer between first and second positions separate from the pulse counter; and a control circuit for calculating a motor torque value from the speed for each of the plurality of positional locations to compare with a plurality of door profile data points. The control circuit takes corrective action if the difference between the motor torque value for each of the plurality of positional locations and the plurality of door profile data points exceeds a predetermined threshold. The control circuit also updates the plurality of door profile data points to the motor torque values for each respective positional location if the predetermined threshold is not exceeded. In another embodiment both speed and position are detected by a slider element, which is connected to the control circuit. In yet another embodiment a sensor detects non-movement of the door during an open/close cycle and stops operation of the motor. As with the '438 patent, the potentiometer provides no external output for indicating door travel position.
U.S. Pat. No. 5,689,236 teaches a remote garage door position indicator comprising a magnetic sensor device; a transmitter device being operatively coupled to the magnetic sensor device, the transmitter device being capable of transmitting electronic signals; a signal interruption device including a plate extending therefrom, in close orientation to an outer plate of a receiver device engaging the magnetic sensors of the sensor device thereby closing the electrical circuit and causing the transmitter device to cease sending electronic signals; and a garage door position indicator including a power source and a light. The position indicator includes the receiver means capable of receiving electronic signals from the transmitter device. When receiving electronic signals from the transmitter, the receiver device causes the light to illuminate. In the closed orientation the transmitter device does not emit electronic signals thereby preventing the receiver device from illuminating the light. Users can then view the light of the position indicator to determine whether their garage door is opened or closed. However, no intermediate positions of the door are provided by the indicator.
U.S. Pat. No. 5,402,105 discloses a garage door position indicating system includes a tilt switch attached to a garage door, an RF transmitter coupled to the tilt switches, an RF receiver, and an indicator controlled by the RF receiver. The tilt switch supplies an enable signal to the RF transmitter at selected first tilt positions and blocks the enable signal at selected second tilt positions. The RF transmitter generates an RF signal in response to the enable signal. The RF receiver is responsive to the RF signal and controls an indicator to indicate the position of the garage door in either an opened or closed position, but no indication is provided for an indication of an in between position.
U.S. Pat. No. 4,954,810 teaches a signaling system for an automated garage door including a transmitter rendered operative upon the opening of the door and a receiver stage which may be adhesively mounted on the remote sending unit by which door operation is signaled. The receiver stage includes a clock and an audio signal generator both of which are disabled by a reset switch. A bar is adhesively affixed to this reset switch and to the sending unit for common manual articulation of a door closing signal and a reset signal. Nothing in this patent discloses that the receiver may receive a blocking signal to disable operation of the door.
U.S. Pat. No. 4,583,081 teaches a door operator system which includes up and down limit switches actuated to the closed position when the door reaches the up and down travel limits. A processor circuit within the operator is connected to the limit switches for ascertaining the position of the door. Bias circuits apply a bias to the processor when the limit switches are open. An indicator system comprising a pair of light emitting diodes connected across respective limit switches indicates the door position. A series impedance element common to both LED circuits prevents actuation of the control circuit by the light emitting devices. But, like the other references, no teaching is provided of an audio or visual indication of an in between door position.
Based upon the foregoing it is evident that there is a need in the art for a device that can indicate the position of a movable barrier anywhere between an open position and a closed position. Moreover, there is a need for an indication of the movable barrier position by either lights, audible tones or a display to indicate the movable barrier's position. There is also a need in the art for the ability to block out signals from transmitters other than a main indicator device.